title: Capsaicin-induced bladder overactivity and nociceptive behaviour in conscious rats: involvement of spinal nitric oxide.
abstract: To investigate the role of nitric oxide (NO) in spinal regulation of lower urinary tract function and bladder nociceptive behaviour, cystometry was performed in conscious rats. The effects of intra-arterial and intrathecal administration of the NO synthase (NOS)-inhibitor, L-NG-nitroarginine methyl ester (L-NAME), were studied on volume- and capsaicin-induced micturitions. The incidence of nociceptive behaviour after intravesical capsaicin was investigated in the absence and presence of L-NAME. Intrathecal L-NAME (0.5 mg) had no effect on the normal, volume-induced micturition. Intravesical capsaicin (30 microM) increased the micturition pressure (p < 0.01), the basal pressure (p < 0.01) and decreased the bladder capacity (p < 0.01) and the micturition volume (p < 0.01). Administration of L-NAME intrathecally (0.5 mg) or intra-arterially (25 mg/kg) had no effects on the capsaicin-induced bladder activity. During capsaicin-infusion, the rats showed signs of distress such as licking and head-turning directed toward the abdomen. This nociceptive behaviour was shown during 31 +/- 3% (n = 6) of the observation period. The capsaicin-induced nociceptive behaviour was markedly reduced by intrathecal and to a less extent by intra-arterial, administration of L-NAME. The percentage time spent licking and head-turning was reduced to 11 +/- 2%, n = 6 (p < 0.001) and 18 +/- 3%, n = 6 (p < 0.05) in rats treated with intrathecal and intra-arterial L-NAME, respectively. The results suggest that NO is not involved in the spinal regulation of the volume- or capsaicin-induced micturition. In contrast, the nociceptive behaviour evoked by intravesical capsaicin seems to involve spinal NO.
authors.affiliation: Department of Clinical Pharmacology, Lund University Hospital, Sweden. katarina.persson@klinfarm.lu.se
authors.forename: R K
authors.initials: RK
authors.lastname: Pandita
authors.forename: K
authors.initials: K
authors.lastname: Persson
authors.forename: K E
authors.initials: KE
authors.lastname: Andersson
mesh_terms: D000283:Administration, Intravesical; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002211:Capsaicin / Q000008:administration & dosage*; D005260:Female; D007278:Injections, Spinal; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009412:Nerve Fibers / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism; D014554:Urination / Q000187:drug effects
chemical_list: D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D002211:Capsaicin; D019331:NG-Nitroarginine Methyl Ester